Crystalline zeolite and method of preparation

ABSTRACT

Crystalline zeolites are prepared by reacting raw kaolinite with aqueous alkali metal hydroxide solutions at temperatures between 80* to 140* C.

O Unlted States Patent 1151 3,663,164 Barrer et al. 51 May 16, 1972 541CRYSTALLINE ZEOLITE AND 2,992,068 7/1961 I-Iaden e161 ..23/11 2 METHODOF PREPARATION 3,009,776 11/1961 SenSel ....23/112 3,010,789 11 1961 Mlt...,23113 [72] Inventors: Richard M. Barret, Bromley, England; l on J hF C l A d N h l d 3,037,843 6/1962 Mason ...23/112 h g iz d 3,123,4413/1964 Haden 6161.. ...23/113 c 3,431,218 3/1969 Plank Cial. ..252/455[73] Assignee: Air products and Chemicals, Inc., Wayne,

p FOREIGN PATENTS OR APPLICATIONS 22 Filed; g,19 9 635,566 l/1962 Canada..23/113 [21] Appl. No.: 864,908 OTHER PUBLICATIONS Barreret al., J.Chem. Soc." 1951 pp. 1,267- 1,278. 1 Foreign Application Priority DataBarrer et al., J. Chem. Soc. 1953 pp. 4029- 4,035.

Oct. 11, 1968 Great Britain ..48,309/68 Primary Examiner-Edward J. Meros52 us. c1 ..23/112,23/113,252/455z Attorney-B Max Klevitand JohnR-Ewbank [51] Int. Cl. ..C01b33/28 [58] Field ofSearch ..23112,113,111;252 sz AB TRACT Crystalline zeolites are prepared byreacting raw kaolinite [56] References cued with aqueous alkali metalhydroxide solutions at temperatures UNITED STATES PATENTS between to2,991,151 7/1961 Breck et al ..23/1I3 2Claims,No Drawings CRYSTALLINEZEOLITE AND METHOD OF 2 Li-K as in Example 1 140 12 hr. PREPARATION 3Li-K as in Example 1 120 15 hr. 4 Li-K as in Example 1 95 15 hr. GENERALBACKGROUND 5 Li-K 0.5g. kaolinite+ 80 64 days lOml. 4.25M LiOH Thisinvention relates to zeolites, crystalline aluminosil- 5 6 Rb-D 1.5 g.kaolinite+ 8O days icates useful as selective sorbents, molecularsieves, ion 7 Rb D 9 2 z so days exchangers and catalysts. 8 C 3 k 20 6da 5 The literature discloses that many methods have been em- 5 1011 1CsOH y ploye d to make zeolites. When the starting material is 9 (ls-Das i Example 1 80 14 y kaolinite, the preparation involved calcining orotherwise 10 Z: 5:22 g 22: dehydrating the kaolinite to convert it tothe amorphous p metakaolinite which was then converted to crystallinezeolite in the presence of aqueous alkali metal hydroxides.

It is the primary object of this invention to provide a method Potassiumcompounds of Considerable diversity were 815 o of making zeolites moreeconomically wherein zeolitization is 15 Obtained at low temperatures bythe action of aqueous KOH ggfstfis the use of raw kaohmte at relanvelylow on raw kaloinite, the products crystallizing from reaction mixturesgenerally at 80 C. At constant temperature the products 5: 2:25; objectof mvem'on to provlde novel specles depend primarily upon the hydroxideconcentration, the den- Other objects of the invention will becomeapparent from 20 my of efkao "w susfmnslon playmg only a mmorfole' thcdescription hereof which follows. A zeolite, herem deslgnated K-l (K 0,A1 0 2510 4H O) The instant method of snythesizing the zeolites wascarried crystall'zed as very hexagonal platfs from L8 to out by placingweighed amounts of raw kaolinite and metered 9 aqueous KOH Solunonsbelow C The hgxagonal volumes of alkali metal hydroxides ofpredetermined concencell Parameters A 35010-3 trations in screw-toppolypropylene bottles or sealed glass An exanfmanon of K4 m a s X'raydlffractometer tubes which were rotated end-over-end in thermostaticallyshowed It to decompose at 168 C0 before 1055 of all controlled airovens. Larger-scale preparations below about Zeollte water- 100 C. weremade with stirring in larger glass reaction vessels Another zeolite,herein designated K-G, a near chabazite, under nitrogen fitted withcondensers and temperature concrystallized from the reaction mixture assmall spherulites at trollers. The crystalline products were separatedon No. 4 80 C. when the KOH concentration was less than 1.8 molalporosity sintered-glass filters, washed and dried and finally and thereaction mixture was not agitated.

stored at about 20 C. over a saturated solution of Ca(NO Another zeolitedesignated (K20, A1203, zsioz 3H20) g il g fg f h lk l 31 d th appearedas lath-like clusters when raw kaolinite was reacted y e50 t e a almet sw use m e g with fairly concentrated KOH in the temperature range ofthose CS been prepare by 35 80l20 C. For example the zeolitecrystallized from reaction reacungKthel'r ulfates i g i 'q f 10%mixtures containing 0.46044, 0.47 and 0.47 grns. of kaolinite one emP haf C :8 per 100 ml. H 0 and 8.7, 11.5, 4.0 and 5.2 molal KOH which i 6gf%i g: g gi g were maintained at temperatures of 80 C., 80 C., 120 C. and0; a; 2 120 C. for 9, l3, 7 and 7 days respectively, and which times 2.:can used p g p Yet another zeolite, herein designated K-Z (K 0, A1 0While the term kaolinite is sometimes employed as the 28102 3'5H2o)appered as i 'f f lath'hke descripfion of a Specific crystalline clayform having the oxide crystals obtained only by reactmg raw kaolinitewith saturated type formulation A1 0. 2SiO ZHQ. it is here employed inits 45 KOH and no excess of water f example the zeohte was broader senseas the mineral characteristics of kaolinite. Acformed h of kaohmte per10 1 was ceptable kaolinite clays may range in composition in the orderreacted saturated KOH (about molal) 80 the of 44 0 470% sioz A1203, losson product was removed from the react1on tube. It IS stable on ignition;along with minor amounts of impurities such as heating to The q q n lostm F i 0.22.0% Fe O 0. l-2.0% TiO and up to several percent of manner grnc balance by heating to 300 the alkaline earth and alkali metal oxidesin varying propor- Was regained by storlng the sample over Saturatedaqueous tions. Ca(NO This feature is of value in that the use of suchTable l which follows lists some of the zeolites formed by Product asdrying agent exhibits slabmty f f f? the foregoing method and theconditions under which the "On-desorption y The P 15 a baslc Zeohte wlthreactions were carried KOH present, apparently as the intercalatedspecies. It ex- TABLE 1 hibits a strong endotherm at 490 C. accompaniedby an increase in the differential weight loss.

lroduct I 'llemp- Similarly reacting raw kaolinite with aqueous NaOH inthe Des'gnamn Mxture manner set forth in Table 1 will also producezeolitic products. I LFA 2g kaolinitfi 140 30 hr A comparison of theX-ray powder patterns of some of the log. LiOH-H,O+ zeolites made by theinstant method appears in the following 30ml. H 0 Table II:

TABLE II.-COMIARTSON 0F d SPACINGS Rb-D Rb-l) K-F Prepn. (1) .lrupn. (2)Cs-D K-Z Li-A Li-K I I I l I l I 7.04 m 7. 05 36 7. 16 w 5. 3?3 m 6.95vs 4.2%) 1 3% 6.93... m 6.55 10 4. 56 w 5.20 s 2. 66 100 6.53... m 5.6510 4.22 w 4. 26 vs 2. 42 30 5.15 9 5. 07 w 4.16 w 4. 08 w 2. 335 254.77... w 4. 05 13 4.87 w 3. 93 w 3.27 w 1. 7110 20 4.45... w 4. s0 123. m 3.17 vs 7. 536 30 4.15... w 3. 54 m 3.02 vs 1. 206 1 10 3.98... w4.00 w in 2.68 vw 2.625 3. 51 m 2 5; 3. 55 m 3. 03 v: 2. 40s

3.0u m 3.011 s 3.00 3.14 s 21:11 3v :1 i

TABLE 1I.--COMPAR1SON OF (l-SPAGINGS -(unlinl|cd RbD Rbl) K-F Prepn. (1)lrcpn. (2) (84) K Z Li K 3.06 vs 2.87 w 2.94... vs 2. 70 w 2.70. VS 2.56vw 2. 53 vw w 2.40 w v 2.34 w

1. 1. 1. 1. 1. 1. 1. 445 1. 1. 1. 1. 1. l. 1. l. l.

l (l(A.). 2 l/lo (burnout). 3 Dillcl'enco.

It will BFQeZn from Table ll that the Rb and Cs zeolites havemodifications and variations without departing from the spirit verysimilar X-ray powder patterns and that these are also similar to thepattern for K-F. Thus all three zeolites are apparently based upon thesame type of aluminosilicate framework. The oxide compositions of thezeolites K-F, Rb- D and CsD are respectively K 0, A1 0 2SiO 3H O; Rb O,M 0 2SiO 2.6H,O and Cs o, M 0 2SiO 2.411 0. All three zeolites possessunusual thermal stability. K-F remained unchanged on heating to 1,000 C.in the thermogravimetric apparatus, and inverted to kaliphilite (K 0, A10 2SiO at l,095 C. Cs and Rb-D inverted to anhydrous phases with similarX-ray powder patterns at l,060 C. and 1,085" C. respectively.

The low temperature crystalline compound of lithium, Li- K, was grownover a range of alkali concentrations between 80 and 140 C., as seen inTable I. Li-A, which replaced Li-K in a reaction of longer duration, isa zeolite of oxide composition Li 0, A1 0 2SiO 411 0. Li-K was alsohydrated, and lost 10.5 percent water smoothly by heating to 500 C Henceits composition is Li O A1 0 2 SiO 2.3 H 0. lts d-spacings are given inTable ll.

The crystalline zeolites Li-A, K-G, K-F, Rb-D and Cs D and K-l, of thisapplication were all found to be ion exchangers of high cation exchangecapacity able to exchange with other alkali-metal ions, alkaline earthmetal ions, ammonium, silver and other cationic species. Selectivity inexchange is of importance in collecting and so concentrating certainions such assilver or radio-nuclides like cesium or strontium. Forexample, K-G is selective for 1(* over Na and the preferential removalof potassium is important in the operation of kidney machines.

All the zeolites of this ivention also have a considerable affinity andsorption capacity for water, which they imbibe selectively.-This makesthem useful as desiccants, especially when the li uids or gases beindried corn rise other molecules una le by reason of s1ze,s ape or lackopolarity to penetrate the zeolite crystals.

Further, the unusual thermal stability exhibited by zeolites K-F, Rb-Dand Cs-D exceeds the environmental demands of usual operations employingand utilizing the sorbent and molecular sieve properties of crystallinezeolites. This increased thermal ceiling provides an increased factor ofsafety and shortened times for thermal desorption treatment.

It will be understood that skilled artisans may make minor of theinvention and the scope of the appended claims.

We claim:

1. A crystalline basic potassium zeolite having a composition 0 A1 0 2SiO: KOH'3.5 H 0,

the KOH and H 0 being intercalated in the potassium aluminodi-silicateframework, the atoms of which composition being arranged in a unit cellin such a manner that the X-ray powder diffraction of the compositionfeatures d spacings as follows:

d(A) l I ss ass sszzzssssa v UNITE -STAT S PATENT OFFICE"C'ERTIFI-CATEOF CORRECTION Patent No. 3. 3, 16Ll D t d May 16, 1972Inventor'(s) Richard M. Barrer, John F. Cole, Hans Sticher It iscertified that error appears in the above-identified"patent and thatsaid Letters Patent are hereby corrected as shown below:

I Column 1, line 37 "CaO=O" should read --CaO=10%--.

Table 2, he co1-umn 35 meaning difference should read 35--.

Table '2; la-s column 19 meaning difference" should read 19--.

Signed and sealed this 9th day of January 1 973.,

(SEAL) Attest:

EDWARD M.FLET( IHER,JR. I ROBERT GOTTSCHALK Attestlng OfficerCommissioner of Patents

2. A method of preparing the basic potassium zeolite of claim 1 whichconsists essentially of the steps of preparing a reaction mixtureconsisting essentially of raw kaolinite and an aqueous solution about 32molal of potassium hydroxide, heating the reaction mixture to about 80*C., maintaining the reaction mixture at about 80* C. for a time periodsufficient for said zeolite to form, and separating the solid productfrom the reaction mixture.